Illumination device having remotely powered lightguide

ABSTRACT

An illumination device is disclosed, having a lightguide optically coupled to a light source and a transducer for supplying power to the light source by converting energy received from a remote transmitter. Energy received from a remote transmitter can comprise radiofrequency waves, microwaves, infrared radiation, visible light, ultraviolet light, sunlight, sound waves or heat.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage filing under 35 U.S.C. 371 ofPCT/US2010/054761, filed Oct. 29, 2010, which claims priority toProvisional Application No. 61/263,495, filed on Nov. 23, 2009 and toProvisional Application No. 61/256,827, filed Oct. 30, 2009, thedisclosure of which are incorporated by reference in their entiretyherein.

FIELD

This disclosure relates to illumination devices, and particularly toillumination devices having lightguides for facilitating distribution oflight emitted by a remotely activated light source.

BACKGROUND

Lightguides are used to facilitate distribution of light from a lightsource over an area much larger than the light source. Lightguidescomprise optically transmissive materials and may have different formssuch as slab, wedge, and pseudo-wedge forms. Most lightguides aredesigned to accept light at an edge surface and allow this light topropagate by total internal reflection between a back surface and anoutput surface, toward an opposing edge surface from which the lightenters. Light is emitted uniformly from the output surface usingextracting features that are positioned in various types of patterns onthe output surface.

SUMMARY

The illumination device disclosed herein includes a lightguide opticallycoupled to a light source and a transducer for supplying power to thelight source by converting energy received from a remote transmitter.Energy received from a remote transmitter can comprise radiofrequencywaves, microwaves, infrared radiation, visible light, ultraviolet light,sunlight, sound waves or heat.

An illumination article comprising the illumination device without thelight source is also disclosed herein, as are methods of providingillumination using the illumination device and article.

These and other embodiments of the invention are described in thedetailed description below. In no event should the above summary beconstrued as a limitation on the claimed subject matter which is definedsolely by the claims as set forth herein.

BRIEF DESCRIPTION OF DRAWINGS

Advantages and features of the invention may be more completelyunderstood by consideration of the following figures in connection withthe detailed description provided below. The figures are schematicdrawings of various articles and are not necessarily drawn to scale.

FIG. 1 is a schematic illustration of an exemplary illumination devicedisclosed herein.

FIGS. 2 a-b, 3 a-b and 4-9 are schematic illustrations of exemplaryillumination devices receiving power from a remote transmitter.

FIG. 10 is a schematic illustration of an exemplary illuminated articlecomprising an exemplary illumination device.

FIGS. 11 a-b are schematic illustrations of watches comprising exemplaryillumination devices.

FIG. 12 is a schematic illustration of a smart-labeled can comprising anexemplary illumination device.

FIGS. 13 a-c are schematic illustrations of a “smart inventory” systemin which an exemplary illumination device is used.

DETAILED DESCRIPTION

This disclosure relates to U.S. Provisional Application Nos. 61/256,827filed on Oct. 30, 2009 and 61/263,495 filed on Nov. 23, 2009 (both toSherman et al.); WO 2010/005655 A2 (Sherman et al.); PCT/US2010/039577(Appeaning et al.); U.S. Pat. No. 7,044,373 B1 (Garber et al.); U.S.Pat. No. 6,407,669 B1 (Brown et al.); U.S. Pat. No. 7,456,744 B2 (Kuhnset al.); and US2003/0004946 A1 (VanDenAvond et al.); the disclosures ofwhich are incorporated by reference herein.

As described in the above-cited Sherman et al. references, light sourcesand lightguides can be used to transform everyday articles such aswatches, labels and medical devices into illuminated versions of thesearticles. However, the light sources are powered by some external powersupply which, in many cases, cannot be readily incorporated into sucharticles or if incorporated, imposes limitations on the design of thearticles.

The ability to power optical sources remotely could impact many lightingapplications such as labels, security and medical devices, andorganizers/containers. Lighted ceiling panels for drop ceilings could beRF (radio frequency) powered from a ceiling grid so that if full contactwith the “wired” grid were not possible, or if tiles of the grid becamemisaligned, the lighting would still function without the need forphysical contact. If the RF power supply included an identificationportion, typically referred to as radio frequency identification (RFID)technology, it could be possible to obtain various types of informationfrom an illuminated article beyond the usual “track and trace” for whichRFID technology is used. For example, RFID technology could be used toprovide information such as a burned out light source or when a lightsource draws too much power from a power supply. Additionally, RFIDtechnology could be used to advertise products, and for systems such asthose used in libraries, could be set up to identify collection ofpurchase fees. This offers the store owner and the consumer benefits atthe same time in the same part.

This invention describes ways to power a light source, such as a lightemitting diode (LED), from a power supply located in either a separatepart of an illuminated article or remotely with no physical connectionto an article to be illuminated. The invention may be achieved byproviding a physical conductive path to transport power to differentparts of an article, or by providing means to transport power wirelesslyusing induction power.

Faraday's law states that a time-varying magnetic field through asurface bounded by a closed path or loop induces a voltage around theloop. When a power supply antenna is in close proximity to a closedantenna coil, a time-varying magnetic field is generated which induces avoltage (called electromotive force or EMF) in the closed antenna coilsuch that a flow of current is produced on the coil. A light sourceconnected to the closed antenna coil can provide illumination ifconnected to the closed antenna coil. For example, as described inExample 1, if an illuminated watchband as a decorative feature ifdesired, the light source could be incorporated into the watchband, andthe power supply for the light source in the watch body. The powersupply could comprise the battery used to power the watch.

Illuminated labels with brand markings can be made as described inExample 2, wherein a viscoelastic lightguide is incorporated into aconstruction of the label on a can. Light sources such as LEDs can bepowered from remote places when the cans are displayed on a store shelfwhich can attracting the attention of customers.

Light sources such as LEDs can be RF powered by rapid pulsation of RFsignals such that the LEDs appear to glow, and intermittent pulsationcan be used to make the LEDs blink. Colored light sources can be poweredusing LEDs which utilize different voltages for color, and colors can beadded or changed with an increase or decrease in signal strength. It isalso envisioned that if two or more RF circuits are utilized in asystem, each circuit having a different color, a watch or label couldpulse one or more of the light sources forming patterns, color changing,etc.

Viscoelastic lightguides such as pressure sensitive adhesive (PSA)lightguides could be used to bond labels to substrates of bottles, suchas a green LED label on a green Prell™ Shampoo bottle or blue LEDs on abottle of Dawn™ dishwashing liquid. A viscoelastic lightguide couldallow for light extraction when bonded to such substrates, and thelabels and/or product could be made to glow using ultraviolet (UV) LEDsor fluorescent compounds in the bottles. Light would be extracted backinto the bottle by attaching the label to the bottle using aviscoelastic lightguide.

Selected areas of labels can be illuminated by incorporating UV LEDs orphosphor pigment in the selected areas while other areas remain dark. Asa result, labels with improved contrast and color brightness can beobtained.

The invention can also be used in medical devices and treatments, suchas for antimicrobial purposes, basic skin optical and drug delivery(such as with IR LEDs). Devices include the light-activatedantimicrobial device described in Appeaning et al which comprises alight source and a light-activated antimicrobial article comprising aphotosensitizer and a viscoelastic lightguide. The use of remotelypowered lightguides in conjunction with bandages and dressings canimprove the ease by which the devices can be applied, as well as reducethe risk of infection associated with the use of bulky wires.

FIG. 1 is a schematic illustration of an exemplary illumination deviceaccording to some embodiments of the invention. Illumination device 100comprises light source 110, lightguide 120 and transducer 130. Lightsource 110 is positioned relative to lightguide 120 such that lightemitted by the light source and represented by rays 111 enters thelightguide. Light within lightguide 120 and represented by single ray121 is transported within the lightguide by total internal reflection.Transducer 130 comprises a power source that induces current, I, topower light source 110.

FIG. 2 a is a schematic illustration of an exemplary illumination deviceaccording to some embodiments of the invention. Illumination device 200comprises transducer 210 that induces current, I, to power light source110. Transducer 210 comprises a receiver that receives energy, E, fromtransmitter 220. In this embodiment, the receiver and transmitter arelocal to each other meaning that they are physically connected.

FIG. 2 b is a schematic illustration of an exemplary illumination deviceaccording to some embodiments of the invention. Illumination device 230comprises transducer 240 that induces current, I, to power light source110. Transducer 240 comprises a receiver that receives energy, E, fromremote transmitter 250. In this embodiment, the receiver and transmitterare remote to each other meaning that they are not physically connected.

The transducer is a device that converts some form of input energy intoelectrical energy such that power is supplied to the light source. Thetransducer comprises an energy input device or receiver in combinationwith a circuit. The transducer can convert electromagnetic, mechanical,thermal, or chemical energy into electrical energy. The transducer istypically a receiver for receiving input energy but can be any devicewhich converts energy into electrical signals. The transducer can beconfigured to receive energy by induction. The transducer may comprisetransparent conductor, transparent polymer, metal, conductive metal,conductive polymer, or a combination thereof.

The remote transmitter used in the invention generally comprises a powersource. Any type of power source can be used, as long as the remotetransmitter is able to provide the necessary energy to the transducerthat powers the light source. The remote power source may generate, forexample, electromagnetic energy, kinetic energy and/or chemical energy.Types of electromagnetic energy include UV and visible light, heat,radiowaves, and microwaves. Remote power sources that may be used togenerate electromagnetic energy include an energy transmitting portion,a circuit and a remote power source.

The transducer is configured to power the light source using inputenergy received from the remote transmitter. In some embodiments, theinput energy comprises electromagnetic radiation. The input energy cancomprise electromagnetic radiation used for telecommunications, referredto herein as radiofrequency (RF) waves, which includes AM and FM radiowaves, short wave radio waves, and television waves. RF waves can have afrequency of greater than 10⁵ m to less than 10⁹ Hz. An appropriatetransducer comprises a receiving antenna for receiving the RF waves anda device for converting the waves into electrical signals. FIG. 3 a is aschematic illustration of an exemplary illumination device used inconjunction with a remote transmitter comprising a transmitting antenna.Illumination device 300 comprises transducer 310 that induces current,I, to power light source 110. Transducer 310 comprises receiving antenna311 for receiving electromagnetic waves from remote transmitter 320comprising transmitting antenna 321.

An RF tag such as those used in RFID technology can be used as thereceiver. The RF tag can be responsive to a particular radio frequencysuch that the tag can power up itself and respond by radiowave tocommunicate information such as a SKU indentifier. For example, acontrol system can provide energy to power up the RF tag and make aquery by sending out RF waves using an antenna. The RF tag may be anintelligent device, comprising a programmed chip used in combinationwith a circuit.

The remote transmitter may transmit electromagnetic radiation. Examplesinclude the 3M™ RFID Tracking Pad that is available from 3M™ Co.;shelving or other components used in “smart shelf” technology; and acell phone or other handheld electronic device.

In some embodiments, the input energy comprises microwaves having afrequency of greater than 1000 to 30,000 MHz. Microwaves can begenerated in electronic devices that produce oscillations at microwavefrequencies. The devices may be single-frequency or tunable, andcontinuous-wave or pulsed. Microwaves can be generated using a gyrotron,klystron, magnetron, backward-wave oscillator, solid-state generatorsuch as a tunnel diode, Gunn diode, IMPATT diode, transistor oscillator,maser, and harmonic generators using varactor diodes. Transmitters formicrowaves include cell phone towers. Receivers for microwaves includeantennas. Transducers for converting microwaves into electrical signalsinclude semiconductors. One example of a semiconductor comprises a PINdiode as described in U.S. Pat. No. 4,673,896 (Brady et al.).Transducers for converting microwaves are also described in U.S. Pat.No. 3,710,283 (Alphonse).

In some embodiments, the input energy comprises infrared (IR) radiation,from the near IR to the far IR frequencies, having a frequency ofgreater than 10¹⁰ to about 5×10¹⁴ Hz. Transducers for converting IRradiation into electrical signals include photodetectors includingphotodiodes, and materials which exhibit the pyroelectric effect such aspyroelectric crystals. Remote transmitters for transmitting IR radiationinclude LEDs that emit IR radiation. Other IR detectors include siliconphotodiodes and silicon photocells. IR remote controls can also be used.

In some embodiments, the input energy comprises visible and/or UV light,having a wavelength of about 200 nm to about 800 nm. Transducers forconverting visible light and/or UV light include photovoltaic cells,photodetectors including photodiodes. Remote transmitters fortransmitting visible and UV light include any of those described belowfor the light sources of the illumination device.

Input energy can be obtained from the sun. FIG. 3 b is a schematicillustration of an exemplary illumination device according to someembodiments of the invention. Illumination device 330 comprisestransducer 340 that induces current, I, to power light source 110.Transducer 340 comprises a solar cell or photovoltaic cell for receivingand converting energy from the sun.

The input energy can comprise kinetic energy used in conjunction with amotion transducer. Kinetic energy, such as kinetic energy resulting froman applied mechanic force, can be in the form of sound waves (about 1 toabout 25,000 kHz). For example, the transducer may comprise a microphonefor receiving sound waves. Remote transmitters for transmitting soundwaves include loudspeakers. Materials which exhibit the piezoelectriceffect, such as piezoelectric crystals, can also be used as motiontransducers. Remote transmitters for generating kinetic energy receivedby the motion transducer include people and animals in motion; and windgathering devices such as windmills (wind power). Other sources ofkinetic energy include wave action from water (hydro power), vibrationfrom mechanical sources, combustion turbines, vibration from roads,railroads, fixed or moving engines. Kinetic energy can be obtained byconverting chemical potential energy such as with combustion ofhydrocarbons, coal and other fuels.

The input energy can comprise heat used in conjunction with a thermaltransducer. Materials which exhibit the pyroelectric effect, such aspyroelectric crystals, can be used as thermal transducers. Thermopilescan convert thermal energy into electrical energy and are comprised ofelectronically coupled thermocouples which can generate an outputvoltage proportional to a local temperature difference or temperaturegradient.

The input energy can comprise chemical energy. Remote power sources thatmay be used to generate chemical energy include fuel cells andbatteries.

The remote power source may be a local power company. The remote powersource may produce AC or DC power. AC sources include nuclear energy,coal, a generator, etc. DC sources include solar cells, batteries, USBcommunication, etc.

FIG. 4 is a schematic illustration according to some embodiments of theinvention. Illumination device 400 comprises light source 110,lightguide 120, and first transducer 410 that induces current, I, topower light source 110. First transducer 410 receives first energy, E,from second transducer 420 which can be either remote or local as shownin FIG. 4. Second transducer 420 receives second energy from remotetransmitter 430. Remote transmitter 430 can be either remote as shown inFIG. 4, or it can be local. The first transducer can comprise any of thetransducers described above for converting input energy into electricalenergy used to power the light source. The second transducer is notlimited to any particular type of transducer, rather, the secondtransducer can be any type of transducer that converts second energyreceived from the remote transmitter to first energy received by thefirst transducer.

FIG. 5 is a schematic illustration according to some embodiments of theinvention. Illumination device 500 comprises light source 110,lightguide 120, and first transducer 510 that induces current, I, topower light source 110. First transducer 510 receives first energy, E,from second transducer 520 which can be either remote or local as shownin FIG. 5. Second transducer 520 receives second energy from thirdtransducer 530 which can be either local or remote as shown in FIG. 5.Third transducer 530 receives third energy from fourth transducer 540which can be either local or remote as shown in FIG. 5. Remotetransmitter 550 can be either remote as shown in FIG. 5, or it can belocal. Each of the second, third and fourth transducers can be any typeof transducer as long as they are matched as described above for FIG. 4.

FIG. 6 is a schematic illustration according to some embodiments of theinvention. Illumination device 600 comprises light sources 601 a, 602 aand 603 a, and corresponding lightguides 601 b, 602 b and 603 b,respectively. Illumination device 600 also comprises transducers 610,620 and 630, each capable of receiving energy transmitted by remotetransmitter 640. In this embodiment, energy transmitted by a remotetransmitter is received by more than one transducer, each transducerconfigured to supply power to a light source.

FIG. 7 is a schematic illustration of an embodiment of the invention.Illumination device 700 comprises light sources 701, 702 and 703connected in series as shown in FIG. 7. Transducer with antenna 710receives energy transmitted by remote transmitter 720. In thisembodiment, energy transmitted by a remote transmitter is received by atransducer configured to supply power to more than one light sourceconnected in series.

FIG. 8 is a schematic illustration according to some embodiments of theinvention. Illumination device 800 comprises light sources 110,lightguides 120, first transducer 810 a comprising first receivingantenna 811 a, and second transducer 810 b comprising second receivingantenna 811 b. Remote transmitter 820 comprises transmitting antenna 821for transmitting RF waves which are received by the first and secondreceiving antennas. In this embodiment, RF waves are transmitted from aremote transmitter, and the RF waves are received by more than onetransducer, each transducer configured to supply power to a lightsource.

FIG. 9 is a schematic illustration according to some embodiments of theinvention. Illumination device 900 comprises light sources 110,lightguides 120, first transducer 910 a comprising first receivingantenna 911 a, and second transducer 910 b comprising second receivingantenna 911 b. Remote transmitter 920 comprises transmitting antennas921 a and 921 b for transmitting RF waves of different frequencies whichare received by the first and second receiving antennas. In thisembodiment, RF waves of different frequencies are transmitted from aremote transmitter, and the RF waves of each frequency are received bydifferent transducers, each transducer configured to supply power to alight source.

The illumination device disclosed herein comprises a lightguide and alight source. Light is emitted by the light source, enters thelightguide, and propagates, reflects, and/or refracts according to thelaw of refraction and the principle of total internal reflection. Thebehavior of light within the lightguide may depend on a variety offactors such as the surface structure of the lightguide, the presence(or absence) of additional substrate(s) in contact with the lightguide,and/or the material compositions of the lightguide and any additionalsubstrate(s) in contact with the lightguide. In addition, the behaviorof light within the lightguide may depend on the angular distribution oflight that enters the lightguide.

The behavior of light with respect to the illumination devices disclosedherein can be described using principles of geometric optics. Theseprinciples are well known and are not presented here; a more detaileddescription can be found in the Sherman et al. references cited above.In general, one may apply the law of refraction and the principle oftotal internal reflection in conjunction with ray tracing techniques todetermine theoretically how varying three dimensional structure,material composition, layer construction, angular distribution of light,etc. can affect the behavior of light for the illumination devices andarticles disclosed herein.

The lightguide may have a refractive index greater than about 0.01,greater than about 0.1, or greater than about 0.5. When an opticalarticle for managing light (such as an extractor) is disposed adjacentthe lightguide, the refractive index difference between the lightguideand the optical article may be from about 0.002 to about 0.5, from about0.02 to about 0.5, from about 0.05 to about 0.5, from about 0.1 to about0.5, or from about 0.4 to about 0.5.

The lightguide may have any bulk three-dimensional shape as is neededfor a given application. The lightguide may be in the form of a squareor rectangular layer, sheet, film, etc. The lightguide may be cut ordivided into shapes as described below.

The thickness of the lightguide is not particularly limited as long asit can function as desired. The thickness of the lightguide may beselected based on or in conjunction with the light source. Exemplarythicknesses for the lightguide range from about 0.4 mil to about 1000mil, from about 1 mil to about 300 mil, from about 1 mil to about 60mil, or from about 0.5 mil to about 30 mil.

The amount and direction of light extracted from the lightguide may becontrolled, at the very least, by the shape, size, number, arrangement,etc. of the features, the refractive indices of the lightguide and anymedium with which the lightguide is in contact, the shape and size ofthe lightguide, and the angular distribution of light that is allowed toenter the lightguide. These variables may be selected such that fromabout 10 to about 50%, from about 20 to about 50%, from about 30 toabout 50%, from about 50 to about 70%, from about 50 to about 80%, orfrom about 10 to about 90% of light is extracted from the lightguiderelative to the total amount of light that enters the lightguide.

In some embodiments, the lightguide is a viscoelastic lightguidecomprising one or more viscoelastic materials. In general, viscoelasticmaterials exhibit both elastic and viscous behavior when undergoingdeformation. Elastic characteristics refer to the ability of a materialto return to its original shape after a transient load is removed. Onemeasure of elasticity for a material is referred to as the tensile setvalue which is a function of the elongation remaining after the materialhas been stretched and subsequently allowed to recover (destretch) underthe same conditions by which it was stretched. If a material has atensile set value of 0%, then it has returned to its original lengthupon relaxation, whereas if the tensile set value is 100%, then thematerial is twice its original length upon relaxation. Tensile setvalues may be measured using ASTM D412. Useful viscoelastic materialsmay have tensile set values of greater than about 10%, greater thanabout 30%, or greater than about 50%; or from about 5 to about 70%, fromabout 10 to about 70%, from about 30 to about 70%, or from about 10 toabout 60%.

Viscous materials that are Newtonian liquids have viscouscharacteristics that obey Newton's law which states that stressincreases linearly with shear gradient. A liquid does not recover itsshape as the shear gradient is removed. Viscous characteristics ofuseful viscoelastic materials include flowability of the material underreasonable temperatures such that the material does not decompose.

The viscoelastic lightguide may have properties that facilitatesufficient contact or wetting with at least a portion of a materialdesigned to extract light from the lightguide, e.g., an optical article,such that the viscoelastic lightguide and the optical article areoptically coupled. Light can then be extracted from the viscoelasticlightguide. The viscoelastic lightguide is generally soft, compliant andflexible. Thus, the viscoelastic lightguide may have an elastic modulus(or storage modulus G′) such that sufficient contact can be obtained,and a viscous modulus (or loss modulus G″) such that the layer doesn'tflow undesirably, and a damping coefficient (G″/G′, tan D) for therelative degree of damping of the layer. Useful viscoelastic materialsmay have a storage modulus, G′, of less than about 300,000 Pa, measuredat 10 rad/sec and a temperature of from about 20 to about 22° C.Viscoelastic properties of materials can be measured using DynamicMechanical Analysis according to, for example, ASTM D4065, D4440, andD5279.

In some embodiments, the viscoelastic lightguide comprises a PSA layeras described in the Dalquist criterion line (as described in Handbook ofPressure Sensitive Adhesive Technology, Second Ed., D. Satas, ed., VanNostrand Reinhold, N.Y., 1989.)

The viscoelastic lightguide may have a particular peel force or at leastexhibit a peel force within a particular range. For example, theviscoelastic lightguide may have a 90° peel force of from about 50 toabout 3000 g/in, from about 300 to about 3000 g/in, or from about 500 toabout 3000 g/in. Peel force may be measured using a peel tester fromIMASS.

In some embodiments, the viscoelastic lightguide comprises an opticallyclear lightguide having high light transmittance of from about 80 toabout 100%, from about 90 to about 100%, from about 95 to about 100%, orfrom about 98 to about 100% over at least a portion of the visible lightspectrum (about 400 to about 700 nm). In some embodiments, theviscoelastic lightguide has a haze value of less than about 5%, lessthan about 3%, or less than about 1%. In some embodiments, theviscoelastic lightguide has a haze value of from about 0.01 to less thanabout 5%, from about 0.01 to less than about 3%, or from about 0.01 toless than about 1%. Haze values in transmission can be determined usinga haze meter according to ASTM D1003.

In some embodiments, the viscoelastic lightguide comprises an opticallyclear lightguide having high light transmittance and a low haze value.High light transmittance may be from about 90 to about 100%, from about95 to about 100%, or from about 99 to about 100% over at least a portionof the visible light spectrum (about 400 to about 700 nm), and hazevalues may be from about 0.01 to less than about 5%, from about 0.01 toless than about 3%, or from about 0.01 to less than about 1%. Theviscoelastic lightguide may also have a light transmittance of fromabout 50 to about 100%.

In some embodiments, the viscoelastic lightguide is hazy and diffuseslight, particularly visible light. A hazy viscoelastic lightguide mayhave a haze value of greater than about 5%, greater than about 20%, orgreater than about 50%. A hazy viscoelastic lightguide may have a hazevalue of from about 5 to about 90%, from about 5 to about 50%, or fromabout 20 to about 50%.

In some embodiments, the viscoelastic lightguide may be translucent inthat it reflects and transmits light.

The viscoelastic lightguide may have a refractive index in the range offrom about 1.3 to about 2.6, 1.4 to about 1.7, or from about 1.5 toabout 1.7. The particular refractive index or range of refractiveindices selected for the viscoelastic lightguide may depend on theoverall design of the illumination device and the particular applicationin which the device may be used.

The viscoelastic lightguide generally comprises at least one polymer.The viscoelastic lightguide may comprise at least one PSA. PSAs areuseful for adhering together adherends and exhibit properties such as:(1) aggressive and permanent tack, (2) adherence with no more thanfinger pressure, (3) sufficient ability to hold onto an adherend, and(4) sufficient cohesive strength to be cleanly removable from theadherend. Materials that have been found to function well as pressuresensitive adhesives are polymers designed and formulated to exhibit therequisite viscoelastic properties resulting in a desired balance oftack, peel adhesion, and shear holding power. Obtaining the properbalance of properties is not a simple process. A quantitativedescription of PSAs can be found in the Dahlquist reference cited above.

Useful PSAs are described in detailed in the Sherman et al. referencescited above. Useful PSAs include poly(meth)acrylate PSAs derived from:monomer A comprising at least one monoethylenically unsaturated alkyl(meth)acrylate monomer, wherein a homopolymer of the monomer has a Tg ofno greater than about 0° C.; and monomer B comprising at least onemonoethylenically unsaturated free-radically copolymerizable reinforcingmonomer, wherein a homopolymer of the monomer has a Tg higher than thatof monomer A, for example, at least about 10° C. As used herein,(meth)acrylic refers to both acrylic and methacrylic species andlikewise for (meth)acrylate.

In some embodiments, the viscoelastic lightguide comprises naturalrubber-based and synthetic rubber-based PSAs, thermoplastic elastomers,tackified thermoplastic-epoxy derivatives, polyurethane derivatives,polyurethane acrylate derivatives, silicone PSAs such aspolydiorganosiloxanes, polydiorganosiloxane polyoxamides and siliconeurea block copolymers.

In some embodiments, the viscoelastic lightguide comprises a clearacrylic PSA, for example, those available as transfer tapes such as VHB™Acrylic Tape 4910F from 3M Company and 3M™ Optically Clear LaminatingAdhesives (8140 and 8180 series).

In some embodiments, the viscoelastic lightguide comprises a blockcopolymer dispersed in an adhesive matrix to form a Lewis acid-basepair. In some embodiments, the viscoelastic lightguide comprises astretch releasable PSA that can be removed from a substrate whenstretched at or nearly at a zero degree angle.

The viscoelastic lightguide can optionally include one or more additivessuch as filler, particles, fibers, bubbles, plasticizers, chain transferagents, initiators, antioxidants, stabilizers, fire retardants,viscosity modifying agents, foaming agents, antistats, colorants such asdyes and pigments, fluorescent dyes and pigments, phosphorescent dyesand pigments, fibrous reinforcing agents, and woven and non-wovenfabrics.

The light source may be optically coupled to the lightguide such that atleast some of the light from the light source can enter the lightguide.For example, a light source may be optically coupled to the lightguidesuch that greater than 1, greater than 10, greater than 20, greater than30, greater than 40, greater than 50, greater than 90%, or about 100% oflight emitted by the light source enters the lightguide. For anotherexample, a light source may be optically coupled to the lightguide suchthat from about 1 to about 10%, from about 1 to about 20%, from about 1to about 30%, from about 1 to about 40%, from about 1 to about 50%, fromabout 1 to about 100%, from about 1 to about 100%, from about 50 toabout 100%, or from about 1 to about 100% of light emitted by the lightsource enters the lightguide. The light source may emit light having arandom or a particular angular distribution.

The light source may comprise any suitable light source. Exemplary lightsources include linear light sources such as cold cathode fluorescentlamps and point light sources such as light emitting diode (LEDs).Exemplary light sources also include organic light-emitting devices(OLEDs), incandescent bulbs, fluorescent bulbs, halogen lamps, UV bulbs,infrared sources, near-infrared sources, lasers, or chemical lightsources. In general, the light emitted by the light source may bevisible or invisible. At least one light source may be used. Forexample, from 1 to about 10,000 light sources may be used. The lightsource may comprise a row of LEDs positioned at or near an edge of thelightguide. The light source may comprise LEDs arranged on a circuitsuch that light emitted from the LEDs lights up continuously oruniformly the lightguide throughout a desired area. The light source maycomprise LEDs that emit light of different colors such that the colorscan mix within the lightguide. In this way, a graphic could be designedto appear differently at different times during its use.

FIG. 10 is a schematic illustration of an exemplary illumination deviceaccording to some embodiments of the invention. Illumination device 1000comprises light source 110, lightguide 120, extractor 1010 opticallycoupled to the lightguide, and transducer 1020. Light source 110 ispositioned relative to lightguide 120 such that light emitted by thelight source and represented by rays 111 enters the lightguide. Lightwithin lightguide 120 and represented by single ray 121 is transportedwithin the lightguide by total internal reflection. Light withinlightguide 120 and represented by single ray 122 is transported withinthe lightguide by total internal reflection and extracted into extractor1010. Transducer 1020 is a power source that induces current, I, topower light source 110.

The extractor may comprise any type of article that can be opticallycoupled to the lightguide. The extractor is typically selected accordingto the intended use of the illumination device. The illumination devicesmay be used in many different types of applications as described in WO2010/005655 A2 (Sherman et al.), and a brief description is includedhere. The illumination devices may be used for signage such as forgraphic arts applications, and on or in windows, walls, wallpaper, wallhangings, pictures, posters, billboards, pillars, doors, floormats,vehicles, or anywhere signage is used.

The illumination devices may be used for safety purposes wherever lightis desired. For example, the illumination devices may be used toilluminate one or more steps of a ladder, steps of a stairway, aislessuch as in airplanes and movie theatres, walkways, egress, handrails,work zone identification signs and markings.

The illumination devices may be used in a variety of items such asreading lights; party and holiday decorations such as hats, ornaments,string lighting, balloons, gift bags, greeting cards, wrapping paper;desk and computer accessories such as desk mats, mousepads, notepadholders, writing instruments; sporting items such as fishing lures;craft items such as knitting needles; personal items such astoothbrushes; household and office items such as clock faces, wallplates for light switches, hooks, tools.

The illumination devices may be used on clothing and clothingaccessories for decorative and/or safety purposes such as on outerwearfor cyclists, on clothing or headgear for miners. The illuminationdevices may be used in wristbands and watch bodies as described below inExample 1 and corresponding FIGS. 11 a-b.

The illumination devices may be used anywhere light is needed ordesired, e.g., on a top or bottom surface of a shelf, or within a shelfhaving a light transmissive portion. The illumination devices may beused as flashlights, e.g., they can be disposed on the outside or insideof a battery cover plate or other part of an electronic handheld device.

The illumination devices may be used with vehicles such as automobiles,marine vehicles, buses, trucks, railcars, trailers, aircraft, andaerospace vehicles. The illumination devices may be used on almost anysurface of a vehicle including the exterior, interior, or any in-betweensurface, e.g., to light up door handles on the exterior and/or interiorof a vehicle, or to illuminate trunk compartments, bumpers, spoilers,floor boards, windows, instrument panels, on or as tail lights, sillplate lights, puddle lights, emergency flashers, center high mountedstop lights, side lights and markers, engine compartments, between theexterior and interior panels of the doors, on cupholders and seats, andthe like.

The illumination devices may be used for traffic safety such as fortraffic signs, street signs, highway dividers and barriers, toll booths,pavement markings, and work zone identification signs and markings, onlicense plates for decoration, or to provide information such as vehicleregistration, etc. The illumination devices may also be used to providelight near license plates such that the license plates are lit up fromthe side, top, etc.

The illumination devices may be used with optical devices comprisinghollow light recycling cavities sometimes referred to as backlightassemblies. Backlight assemblies may be used for signage or generallighting. Exemplary backlight assemblies are disclosed in WO 2006/125174(Hoffman et al.) and US 2008/0074901 (David et al.) all incorporatedherein by reference. The illumination devices disclosed herein may beused to replace the light sources described in these references.

The illumination devices may be used on or in display devices such ascell phones, personal digital devices, MP3 players, digital pictureframes, monitors, laptop computers, projectors such as mini-projectors,global positioning displays, televisions, etc. The illumination articlesmay be used in place of conventional lightguides used to backlight adisplay panel of the display device such as those having LCD and plasmadisplay panels. Exemplary display devices are described in US2008/232135 A1 (Kinder et al.) and U.S. Pat. No. 6,111,696 (Allen etal.). The illumination devices may also be used for lighting buttons andkeypads in various electronic devices including such display devices.

The illumination devices disclosed herein may be incorporated intosecurity films or laminates used to make driver licenses, passports,tamper proof seals and the like, and in the construction of illuminatedlicense plates. The illumination devices disclosed herein may be usedfor creating three-dimensional (3D) images in displays, buttons, keypadsand the like.

The illumination devices disclosed herein may be used insensing/detecting devices wherein a sensor is disposed to receive lightemitted from the viscoelastic lightguide. Also disclosed is asensing/detecting device in which the light source is replaced with asensor/detector. The sensor/detector can be a photodetector, a siliconphotodiode, an IR detector, a solar cell, or an optoelectronic device,or some combination thereof.

The illumination devices disclosed herein may be incorporated into atherapeutic device. For example, the optical articles and devicesdisclosed herein may be used in conformal patches for providing lighttherapy to tissue. Exemplary conformal patches are described in U.S.Pat. No. 6,096,066 (Chen et al.), incorporated herein by reference.Additional therapeutic devices are described in U.S. 2005/0070976 A1(Samuel et al.); Electronics World, October 2007; and LEDs Magazine,November 2006; all of which are incorporated herein by reference.

The terms “in contact” and “disposed on” are used generally to describethat two items are adjacent one another such that the whole item canfunction as desired. This may mean that additional materials can bepresent between the adjacent items, as long as the item can function asdesired.

EXAMPLES Example 1 Illuminated Watchbands

FIG. 11 a shows a schematic drawing of watch 1100 comprising body 1110and illuminated watchband 1120. Battery 1130 as power supply ispositioned in recess 1111 of the body, and LEDs 1135 are embedded in thewatchband. Battery 1130 is connected to LEDs 1135 with wires shown ascurved dotted lines 1137 a-b for simplicity. The wires are connected toconductive locking pin 1140 that holds the watchband in place whenassembled with the body. The locking pin can be constructed in threesegments with two conductive ends and a non conductive middle. Thelocking pin can also comprise two separate pins inserted from each sidesuch that the pins do not touch in the middle being separated by air ornonconductive material. The pin(s) provide the electrical connectionfrom battery 1130 to LEDs 1135 such that the LEDs illuminate watchband1120 as indicated by arrows 1136.

FIG. 11 b shows an embodiment of watch 1150 in which battery 1100supplies power to LEDs 1135 by induction. Wires shown generically asdotted line 1160 a connect battery 1100 to induction coil 1161 a, andwires shown generically as dotted line 1160 b connect LEDs 1135 toinduction coil 1161 b. Alternatively, induction coils 1161 a and 1161 bcould be replaced with RF transmitting and receiving antennas,respectively, such that the LEDs are powered remotely be RF signals. Thecloseness of the watch body and band is certain and the Send would be inthe watch body, while the pick up/receiver could be located in the watchband where it could power the needed light source.

For the embodiments shown in FIGS. 11 a-b, the battery and LEDs can belocated in any combination of body and watchband. For example, thebattery could be located in one or both watchbands, and/or the LEDs canbe located in the body to light the watch face.

A watch body could be used with different watchbands as desired by thewearer.

Example 2 Illuminated Labels

A coil antenna tuned to the a 3M™ badging device was wired to 3 LEDs inseries. Upon placing the antenna close (1 inch or less) to the badgereader, the LEDS would power on and could be observed to light upbrightly.

A device was assembled as by placing three LEDS in both optical andphysical contact with an edge of a layer of a viscoelastic lightguide(VEL). The LEDs were wired in series and connected to a coil antennatuned to a 3M™ badging device. A graphic was adhered to one surface ofthe VEL and the opposing surface of the VEL was adhered to a plasticbottle. The VEL held the graphic to the bottle and the LEDs were alsoheld in the VEL. Upon bringing this bottle with this “VEL Label” closeto the badging device (within an inch), the LEDs powered on and lightwas seen illuminating the graphic on the bottle.

Example 3 Illuminated Labels

FIG. 12 shows smart-labeled can 1200 comprising label 1210 adhered tocan 1220. Embedded within the label (or behind the label) are three LEDs1230 wired in series and in communication with RF receiving antenna1240.

FIGS. 13 a-c show schematic illustrations of a “smart inventory” systemin which smart-labeled cans 1300 emit light when displayed on smartshelf 1310 having a power transmitter (not shown) across top surface1312 of the shelf. The cans are tracked by RFID from an inventorywarehouse to the store and shelf where they are displayed. Light is notbeing emitted by smart-labeled can 1302 until it is placed on smartshelf 1310 to form smart-labeled cans 1320. Light is not emitted bysmart-labeled can 1342 after it has been taken off smart shelf 1310leaving smart-labeled cans 1342.

The closeness of a labeled can and power transmitter is certain as mostlabeled products are displayed on a shelf for consumption and purchase.The Send would be located in or on the shelf (maybe in a separatepowered mat or sheet) where the product with the receiving LEDilluminated label is to be displayed, while the pick up/receiver couldbe located in the label where it could power the needed light source toilluminate the label on the product only when placed on the power matthat is on the shelf. This means that the LEDs in the label will only belit when the product is on the display and not during shipping, storagein warehouse or other non visible or needed places in the supply chaincycle. Illustration is shown in the figure below. The remote powersource may be located in a shelf, display case for jewelry and otheritems, coat rack, refrigerator, cooler for cans.

Example 4 Bandages and Wound Dressings

A bandage or wound dressing could be equipped with a lightguide, a lightsource and a transducer having an RFID induction powered antenna. Lightemitted by the light source could be used for antimicrobial treatment.

What is claimed is:
 1. An illumination device comprising a light source, a lightguide optically coupled to the light source, and a transducer configured to power the light source by converting energy received from a remote transmitter; wherein the lightguide is viscoelastic.
 2. The illumination device of claim 1, wherein the energy comprises radiofrequency waves.
 3. The illumination device of claim 1, wherein the energy comprises microwaves.
 4. The illumination device of claim 1, wherein the energy comprises infrared radiation.
 5. The illumination device of claim 1, wherein the energy comprises one or more of visible light, ultraviolet light, and/or infrared radiation.
 6. The illumination device of claim 1, wherein the energy comprises sound waves.
 7. The illumination device of claim 1, wherein the energy comprises heat.
 8. The illumination device of claim 1, wherein the transducer comprises a piezoelectric material.
 9. The illumination device of claim 1, wherein the transducer comprises a pyroelectric material.
 10. The illumination device of claim 1, wherein the transducer comprises a receiving antenna for receiving radiofrequency waves, and the remote transmitter comprises a transmitting antenna for transmitting radiofrequency waves.
 11. The illumination device of claim 1, wherein the transducer comprises a solar cell.
 12. The illumination device of claim 1, wherein the transducer is a first transducer, and the remote transmitter is a second transducer.
 13. The illumination device of claim 1, wherein the transducer receives energy by induction.
 14. The illumination device of claim 1, wherein the transducer comprises transparent conductor, transparent polymer, metal, conductive metal, conductive polymer, or a combination thereof.
 15. The illumination device of claim 1, wherein the lightguide is a pressure sensitive adhesive.
 16. The illumination device of claim 1, further comprising an extractor optically coupled to the lightguide.
 17. The illumination device of claim 16, wherein the extractor comprises a radio frequency identification tag.
 18. The illumination device of claim 16, wherein the extractor comprises a watch or clock.
 19. The illumination device of claim 16, wherein the extractor comprises a sign or marking.
 20. The illumination device of claim 16, wherein the extractor comprises an indicator light.
 21. The illumination device of claim 16, wherein the extractor comprises a bandage or dressing.
 22. A method of providing illumination, comprising: providing the illumination device of claim 1, and transmitting energy from the remote transmitter to the transducer such that power is supplied to the light source. 